Influenza is an acute respiratory infection, which causes numerous deaths each year. A virus of the orthomyxovirus family, which occurs in three forms, influenza A, B, and C causes the disease. Influenza types A and B cause an acute febrile infection of the respiratory tract characterized by the sudden onset of fever, malaise, headaches, myalgias, and cough. In healthy adults this infection is usually a benign self-limiting condition. In children, the elderly and the immunocompromised, influenza infection can be associated with substantial mortality and morbidity. School-aged children play a central role in the dissemination of influenza in the community. Epidemic attack rates of up to 60% to 70% have been described in school children. Influenza virus infection is rapidly and efficiently spread by aerosol inhalation between individuals. Influenza neurominadase is considered important for sustained viral replication in humans and is thought to play a role in movement of the virus through mucus in the respiratory tract. Inhibition of the enzyme therefore has potential as a target for the development of compounds for the treatment and prophylaxis of influenza infections. In vitro and in vivo data have shown that Ro 64-0796 has potential as a novel oral compound for the treatment of influenza A and B infections. This study is designed to investigate the tolerability, safety, and therapeutic drug levels of Ro 64-0796 in children with influenza. This is a phase III study designed to study the effect of 2 mg/kg of Ro 64-0796 b.i.d. versus placebo for five days in male and female children ages 1-12 with influenza. The study will involve five days of double-blind treatment followed by a follow-up period of 23 days for a total of 28 days. The objectives of this study are to investigate the effect of treatment with Ro 64-0796 on children with influenza and how this treatment may impact medical and other healthcare resources associated with influenza and its complications. The study will also investigate the safety and tolerability of Ro 64-0796 in children with influenza and how it effects viral activity. Information on plasma concentrations of the treatment will be collected, thereby helping to characterize any pharmacokinetic differences within this population.